1) Field of the Invention
The present invention relates to an interleaver and a deinterleaver that respectively shuffle data and restore the order of data in a communication system. More particularly, the present invention relates to an interleaver, a deinterleaver, a communication device, and a method for trans-communication channel interleaving and deinterleaving, by which data can be sorted across a plurality of communication channels.
2) Description of the Related Art
A communication device deployed in a conventional communication system is explained first. Error bursts due to fading are common in communication systems like wireless LAN802.11 or HISWAN, etc. To counter the error bursts, these communication systems perform bit interleaving on the data that is subjected to an error correction coding. To be specific, an interleaver at the transmitter end shuffles the order of the data that is subjected to error correction coding, while a deinterleaver at the receiver end restores the original order of the data. The processes of interleaving and deinterleaving randomize the occurrence of burst errors and reduce data error.
A conventional communication system stipulated by the wireless LAN standards 802.11a set down by the United States (see Institute of Electrical and Electronic Engineers (IEEE) Standards 802.11a-1999) is explained next. The transmitter at the transmitting end subjects the information data to error correction coding, and shuffles the order of the data (conventional method of interleaving). The transmitter further modulates the shuffled data by a predetermined modulation method, and transmits the data. At the receiver end, the modulated data is demodulated, and the original order of the data is restored, after which the data is decoded.
However, the communication device in the conventional communication system has the following problems.
FIG. 8A and FIG. 8B are drawings illustrating an interleaving method deployed in the conventional communication system. Specifically, FIG. 8A represents a Binary Phase Shift Keying (BPSK) interleaver that shuffles data by writing horizontally and reading vertically. FIG. 8B represents a Quadrature Phase Shift Keying (QPSK) interleaver, which also shuffles data like the BPSK interleaver, that is, by writing horizontally and reading vertically. The size and the shape of the interleaver created are specific to the modulation method, and closing of the interleaving process is independent of the communication channel.
However, in a communication involving a plurality of communication channels, if the interleavers are closed independently in all the communication channels as in the conventional communication system, deterioration in communication conditions in one of the communication channels (that is, if one of the communication channels is affected by interference, etc.) leads to a significant reduction in the throughput.